Amplifiers of this type are generally known, and are used to amplify an incoming optical signal.
In this regard, a distinction is made between regenerative and non-regenerative amplifiers.
A regenerative amplifier is composed of a gain medium, an optical resonator, and an optical switch which is used to couple/decouple laser radiation into and out of the resonator, respectively. As a result, in a regenerative amplifier the signal to be amplified is amplified by the gain medium within a resonator over a plurality of passes on the same beam path.
In contrast, a resonator is not present in a non-regenerative amplifier. In other words, a non-regenerative amplifier is an amplifier without a resonator. In a non-regenerative amplifier, the signal to be amplified may be amplified in a single pass through the gain medium. However, it is also possible to amplify the signal to be amplified by passing the signal through the gain medium multiple times on different beam paths. Accordingly, a non-regenerative optical amplifier has neither an optical resonator nor an optical switch. In the simplest case, the non-regenerative optical amplifier is composed solely of an optical gain medium and an excitation light source.
An optical oscillator is known from “Operational characteristics of dual gain single cavity Nd:YVO4 laser” (PRAMANA-J. phys., Vol. 58, No. 1, January 2002) which has a resonator in which two Nd:YVO4 laser crystals as gain media are situated.
An optical oscillator having two gain media is also known from DE 10 2010 008 170 A1.
A mode-coupled oscillator is known from “Generation of sub-40 fs pulses from a mode-locked dual-gain-media Nd:glass laser” (Appld. Phys. B 74 (Suppl.), pp. 177-179 (2002)) which has a resonator in which two different laser crystals as gain media are situated.
A similar mode-coupled oscillator is also known from U.S. Pat. No. 5,956,354.
A regenerative optical amplifier is known from “Regenerative thin disk amplifier with combined gain spectra producing 500 μJ sub 200 fs pulses” (May 11, 2009/Vol. 17, No. 10/Optics Express, pp. 8046ff.) in which different optical gain media are used.
A similar regenerative amplifier is also known from “Ultrafast double-slap regenerative amplifier with combined gain spectra and intracavity dispersion compensation” (Oct. 11, 2010/Vol. 18, No. 21/Optics Express, pp. 21973ff.).
A laser is known from U.S. Pat. No. 5,956,354 which has a resonator in which two different laser crystals as optical gain media are situated.
A non-regenerative optical amplifier is known from U.S. Pat. No. 6,144,484 which has a laser crystal as gain medium and which is based on the continuous wave (CW) emission principle.
A non-regenerative optical amplifier is known from U.S. Pat. No. 7,796,671 which has a laser crystal with multiple passes as gain medium.
Optical fiber amplifiers having multiple optical fibers coupled in succession are known from US 2009/0274183 A1, for example.
A laser system is known from US 2009/0279577 A1 in which a ceramic laser material having a doping gradient is used as gain medium.
A mode-coupled optical resonator is known from US 2006/0092993 A1 which has a plurality of gain media situated in succession along the optical axis.
A laser oscillator is known from U.S. Pat. No. 7,894,501 B2 (corresponding to EP 1 879 271 A2) which has a plurality of gain media.
Laser systems having a plurality of gain media are also known from WO 98/59399 and U.S. Pat. No. 5,930,283.
In addition, disk lasers are known which have a plurality of gain media. Disk lasers of this type are disclosed in EP 1 677 394 A1, US 2002/0075934 A1, U.S. Pat. No. 5,926,494, US 2001/0038658 A1, WO 00/25394, and EP 0 556 977 A1, for example.